1. Field of the Invention
The invention relates to a rotating electric machine, and in particular, to a rotating electric machine in which a coolant is supplied to a gap between the inner periphery of a stator and the outer periphery of a rotor so as to effect cooling.
2. Description of Related Art
Rotating electric machines are cooled since coils generate heat in operation. In a cooling structure for a rotating electric machine as disclosed in, for example, Japanese Patent Application Publication No, 2006-067777 (JP 2006-067777 A), a rotor is provided with slots formed in respective steel sheets of a laminated steel plate to be shifted in phase by 90 degrees in the circumferential direction, such that the slots form passages that extend in radial directions from a coolant passage formed inside a rotor shaft to the outer periphery of the rotor.
In a cooling structure for a motor, as disclosed in Japanese Patent Application Publication No. 2011-125090 (JP 2011-125090 A), protrusions or grooves that are angled relative to the rotational direction are formed at the outer periphery of a rotor, so that a cooling fluid between the rotor and a stator can easily flow toward axially end portions of the rotor.
In a rotor structure of a rotating electric machine, as disclosed in Japanese Patent Application Publication No. 8-275421 (JP 8-275421 A), helical grooves are formed in the outer periphery of a rotor, so as to produce cooling wind using the centrifugal force generated during rotation.